This passage from Family: Monastery of the New Dark Ages has been making me think -- it is by Father Fessio and the whole article is worth reading:
"I was hiking in the Sierra Nevada mountains last week, near Yosemite, surrounded by a very beautiful, magnificent landscape. One of the really striking features is that up in the high Sierra of Yo semite it’s almost all granite; and yet you look on these sheer granite cliffs and these enormous granite mountains, and there are pine trees growing out of the granite. There’s no dirt; it’s just granite. And you see a pine tree coming right out of that granite. How does that happen? A seed has fallen into a crack, taken in moisture, and has been able to grow and crack that granite and it’s been able to live there. That’s why Christ tells us about the parable of the mustard seed, and many parables of seeds in Scripture. The seed has the power which can overcome obstacles much mightier than itself. This we see in Christ Himself as the one who is the seed that becomes incarnate in the womb of the Blessed Virgin in the little backwater town of Nazareth. "